u-boot-brain/doc/README.plan9
Steven Stallion eeaef5e430 cmd_bootm: Add command line arguments to Plan 9
This patch introduces support for command line arguments to Plan 9.
Plan 9 generally dedicates a small region of kernel memory (known
as CONFADDR) for runtime configuration.  A new environment variable
named confaddr was introduced to indicate this location when copying
arguments.

Signed-off-by: Steven Stallion <sstallion@gmail.com>
[trini: Adapt for Simon's changes about correcting argc, no need to bump
by 2 now]
Signed-off-by: Tom Rini <trini@ti.com>
2013-06-26 10:25:22 -04:00

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Plan 9 from Bell Labs kernel images require additional setup to pass
configuration information to the kernel. An environment variable named
confaddr must be defined with the same value as CONFADDR (see mem.h).
Use of this facility is optional, but should be preferable to manual
configuration.
When booting an image, arguments supplied to the bootm command will be
copied to CONFADDR. If no arguments are specified, the contents of the
bootargs environment variable will be copied.
If no command line arguments or bootargs are defined, CONFADDR is left
uninitialized to permit manual configuration. For example, PC-style
configuration could be simulated by issuing a fatload in bootcmd:
# setenv bootcmd fatload mmc 0 $confaddr plan9.ini; ...; bootm
Steven Stallion
June 2013